Biomonitoring

In September 2006, Governor Schwarzenegger signed Senate Bill 1379 authored by Senator Perata, establishing the first State Biomonitoring Program in the nation. Under this new biomonitoring program, California will measure the toxic chemicals accumulating in the bodies of Californians, to give us a snapshot of which chemicals in Californians are rising, which are falling, and which are Emerging Chemicals of Concern that need targeting for pollution prevention.

DTSC will use information on levels of chemicals in humans and wildlife to identify problem chemicals, understand where to focus and prioritize its cradle-to-cradle efforts, and use as an important indicator to measure the success of its interventions.

Bio-accumulation of Environmental Pollutants in Human Body

There is increasing evidence of man-made chemicals detected in the bodies of humans and other animals. These include a class of chemicals known as Persistent Organic Pollutants (POPs). Many of the POPs build up (bio-accumulate) in the tissues of humans and animals. Bio-accumulation occurs when an organism absorbs a toxic substance at a rate greater than that at which the substance is lost. The existing body of information identifies POPs in human cord blood, breast milk and body fat.

Biomonitoring is a common term used when referring to the measurement of concentrations of chemicals and physical agents (i.e., dust, etc.) in the blood and tissues of humans or wildlife. These measured concentrations are commonly referred to as the “body burdens” of these agents. Most of the newer emerging chemicals of concern, or ECCs, have been identified by results from biomonitoring which measured their increasing presence in humans and wildlife.

DTSC scientists have been conducting pioneering biomonitoring studies to determine the levels of many ECCs in humans (blood, breast milk, and urine), as well as the levels of ECCs in wildlife.

The following are a few examples of ECCs that have been found by researchers around the world during biomonitoring studies of humans:

PBDEs: Polybrominated diphenyl ethers (PBDEs) have been widely used as flame retardants in home and office building materials, motor vehicles, electronics, furnishings, textiles, high-temperature plastics and polyurethane foams. Historically, three commercial mixtures of the PBDEs have been manufactured and used – the penta, octa, and deca brominated diphenyl ether (BDE) formulations. The general public is exposed to PBDEs through the use of consumer products in homes, offices, cars and schools. Exposures to PBDEs in some occupational settings, e.g., in computer recycling facilities, can be much higher than those of the general public. As consumer products are used and after they are discarded, PBDEs are released into the environment where they can bioaccumulate in wildlife and food animals. PBDEs have been measured in house and office dust, indoor air, plant and animal-based foods, terrestrial and marine animals, and in human breast milk, blood and fat. The levels of PBDEs measured in humans in the United States and Canada are typically at least 10 times higher than those in Europe, and appear to be doubling every few years. Cal/EPA scientists have reported the highest tissue concentrations of PBDEs measured in the world in California wildlife (shorebird eggs and fish), and rapid accumulation of PBDEs in the tissues of San Francisco Bay harbor seals.

PBDEs have structural similarities to some of the polybrominated and polychlorinated biphenyls (PBBs and PCBs), and to certain other persistent polyhalogenated organic pollutants. In the limited toxicity testing to date, PBDEs have produced some of the toxic effects and physiologic changes typical of many persistent polyhalogenated organic pollutants, in particular the PBBs and PCBs. These effects include developmental and nervous system toxicity, as well as mimicry of estrogen and interference with the activity of thyroid hormone. In addition, there is the potential for brominated dioxins and related compound formation during combustion of plastics containing PBDEs. Neither pentaBDEs nor octaBDEs have been tested for carcinogenicity.

Starting in June 2006, California became the first state to ban pentaBDEs and octaBDEs in new products. DecaBDE is not affected by the recent legislation, and continues to be widely used as a flame retardant on consumer products. There is active research worldwide into its potential release, fate and transport in the environment. Direct exposure to decaBDE appears to pose lower human health risks than those of the other PBDEs, due to its lower toxicity, absorption, and generally lower environmental concentrations. DecaBDE is the predominant PBDE measured in house and office dust. Also, levels of decaBDE found in electronic waste and sewage sludge, suggest that decaBDE from the indoor environment may be released through waste streams and municipal sewage systems into the environment. Potential risks from such releases into the environment require further evaluation. One study in mice with relatively high concentrations of decaBDE showed similar toxic effects on the developing nervous system as with pentaBDE. However, further study is needed to confirm the significance of this finding and to clarify the potential for other toxicological effects from decaBDE.

Use of decaBDE may result in exposure to lower brominated PBDEs of greater toxicological concern. Recent studies indicate that decaBDE breaks down by the actions of sunlight, heat, and bacteria to other PBDEs that contain fewer bromine atoms. Such compounds are also formed through metabolism in certain animals consumed by humans (i.e., fish and chicken). These lower brominated PBDE congeners can undergo further debromination or transformation. The extent and pathways of debromination and degradation of decaBDE under environmental conditions also need further study.

Phthalates: Phthalate acid esters (phthalates) are used extensively as plasticizers in a wide range of applications, such as children’s toys, food packaging, and medical supplies. Some of the phthalates mimic estrogens and have been associated with a host of health problems in rats, including cancer and teratogenicity. Governments in Europe and Japan have become increasingly concerned about levels in food packaging materials and children’s toys. U.S. manufacturers voluntarily removed phthalates from baby items in 1998. The 2001-02 National Health and Nutrition Examination Survey (NHANES) reported twelve phthalate metabolites in urine. Recent data in animals and humans suggest that maternal phthalate levels are linked with adverse effects in offspring on male genitalia and reproductive function.

PFOA and PFOS: Perfluorinated compounds that release PFOA (perfluorooctanoic acid) and PFOS (perflourooctyl sulfonates) have received international attention recently, as these chemicals persist in tissues and have been detected at elevated levels in humans. PFOAs and PFOSs are components of many products, including non-stick cookware, stain-resistant fabrics in upholstery and clothing, electrical wiring, and food packaging, and are emitted through the use of consumer products into food and into indoor air. There is experimental evidence suggesting that these compounds may affect reproduction and development in humans and wildlife, and U.S. EPA’s Science Advisory Board in 2006 called PFOA a likely carcinogen. These ECCs are not directly regulated by any California agency at this time.

Pharmaceuticals: Studies have shown that prescription and non-prescription drugs, germ-killing chemicals and related wastes are finding their way through our sewer systems and into lakes and streams around the country. In many places, the advice given for disposal of unused or expired medications is to flush the old pills down the toilet. Now that these wastes are showing up in small amounts in aquatic organisms, waste managers are rethinking that strategy. No one was aware that these chemicals were passing through the sewage treatment plants and into the environment until methods became available that could detect very small amounts of such chemicals, and until scientists thought to look for them or detected them unexpectedly when studying other chemicals, You can learn more about this emerging waste issue on the No Drugs Down The Drain web site.